1. Field
The present invention relates to the field of communications. More particularly, the present invention relates to a system and method for maintaining anonymous and traffic analysis resistant communications over a communication link.
2. Related Art
Over the last few years, personal and commercial usage of the Internet has increased dramatically. As a result, companies are beginning to monitor such usage for a number of reasons. For example, marketing companies can analyze Internet traffic in order to develop consumer profiles of various users or to obtain information about ongoing projects by a competitive company.
In an attempt to thwart data collection through traffic analysis and provide message anonymity over public communication links like the Internet, anonymous remailers are now being provided. An xe2x80x9canonymous remailerxe2x80x9d is a computer that receives an electronic message over a communication link from a sender and redirects that electronic message to an intended recipient. By encrypting audible and/or viewable data of the electronic message, the integrity and confidentiality of that data would be protected against unauthorized access by the operator of the anonymous remailer or an interloper.
It is evident that the above-described conventional communication scheme would substantially ensure the preservation of the integrity and confidentiality of data within an electronic message. However, this conventional communication scheme fails to protect the integrity or confidentiality of data transmitted back to the original sender in the form of a response from the intended recipient.
In certain situations, anonymous remailers have been configured to assign a unique tag to each original sender of an electronic message before the electronic message is redirected to the intended recipient. This tag is used as a secret key by the intended recipient to encrypt data contained in a response to the electronic message. However, to support this communication scheme, the anonymous remailer would have to decrypt the response with the tag and re-encrypt the response with the public key of the original sender because the intended recipient would have no knowledge of the original sender, namely a public key of the original sender. Since the operator responsible for the anonymous remailer would have access to the return path of the response, reliance on the integrity of that operator is required. Clearly, this substantially reduces the level of security of this communication scheme.
Therefore, it would be desirable to create an electronic system and a corresponding method for maintaining anonymous and traffic analysis resistant communications over a communication link without dependence on the integrity of the system operator.
In one embodiment, the present invention relates a cryptographic device comprising a memory and a processor. The memory is used to contain at least one key. The processor includes circuitry to determine whether a response to an incoming electronic message is requested. The circuitry further encrypts an address of a system associated with the cryptographic device with the key when the response is requested, and assists in placing the encrypted address into an outgoing electronic message before transmission.